Orthopedic Fixation Strut Swapping

ABSTRACT

A plurality of three-dimensional fixator graphical representations may include graphical indications of a strut swap range. A plurality of replaced strut graphical representations may change from a first rendering state in a swap start fixator graphical representation to a second rendering state in a swap end fixator graphical representation. A plurality of replacement graphical representations may change from the second rendering state in the swap start fixator graphical representation to the first rendering state in the swap end fixator graphical representation. In some examples, the plurality of replaced strut graphical representations may gradually fade out from a swap start stage to a swap end stage, and the plurality of replacement strut graphical representations may gradually fade in from a swap start stage to a swap end stage. Additionally, a treatment plan including at least one interfamily strut swap may be generated for manipulating a fixator to correct a deformity.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No. 16/356,310 filed Mar. 18, 2019, the contents of which are hereby incorporated by reference in their entirety.

BACKGROUND

Techniques used to treat fractures and/or deformities of anatomical structures, such as bones, can include the use of external fixators, such as hexapods and other fixation frames, which are surgically mounted to anatomical structure segments on opposed sides of a fracture site. A pair of radiographic images is taken of the fixator and anatomical structure segments at the fracture site. Data from the images is then manipulated to construct a three-dimensional representation of the fixator and the anatomical structures segments that can be used in developing a treatment plan, which may for example comprise realigning the anatomical structure segments through adjustments to the fixator.

Existing techniques for controlling fixator manipulation may, however, involve a number of limitations that may introduce inefficiency, complication, and unreliability. In particular, the manipulations to the fixator may include one or more strut swaps, which is a swap (i.e., exchange) of a replaced strut for a different sized replacement strut by removing the replaced strut from the fixator and replacing it with the replacement strut. There may typically be a specified range of time in which a strut swap may be performed, referred to as a strut swap range. Certain conventional techniques may be limited with respect to the ability to indicate when strut swap ranges occur (e.g., on which days of a treatment plan a strut swap may be performed) to users in a clear and efficient manner. These techniques may also be limited with respect to the ability to indicate an amount (e.g., percentage) of a strut swap range duration that is remaining and/or that has expired at any particular day within the strut swap range. Additionally, in some examples, although multiple different types or families of struts (e.g., standard, quick adjust, etc.) may sometimes be available for use with a fixator, users may often be limited to selecting and using struts from only a single family. This is because some techniques may not allow calculation of treatment plans that include interfamily strut swaps (i.e. swaps of struts between different strut families). This may be problematic, for example, because struts from different families may have different length ranges, and some corrections may require a shorter or longer length than is available from a particular selected strut family.

SUMMARY

Techniques for orthopedic fixation strut swapping are described herein. In some examples, a plurality of fixator graphical representations, such as three-dimensional graphical representations, may be provided of a fixator that includes rings and struts to correct a deformity of first and second anatomical structure segments. Specifically, a computing system may first determine manipulations to the fixator for correction of the deformity. The manipulations may comprise a plurality of adjustments to strut lengths and a strut swap from a replaced strut to a replacement strut. The manipulations may be performed throughout a set of stages (e.g., days), and the strut swap may be performable in a strut swap range comprising a sub-set of stages within the set of stages. The sub-set of stages may include a swap start stage and a swap end stage. The computing system may then generate the plurality of fixator graphical representations. The plurality of fixator graphical representations may include a swap start fixator graphical representation and a swap end fixator graphical representation. Each of the plurality of fixator graphical representations may include a respective one of a plurality of replaced strut graphical representations and a respective one of a plurality of replacement strut graphical representations. The plurality of replaced strut graphical representations may change from a first rendering state in the swap start fixator graphical representation to a second rendering state in the swap end fixator graphical representation. The plurality of replacement strut graphical representations may change from the second rendering state in the swap start fixator graphical representation to the first rendering state in the swap end fixator graphical representation. In some examples, the first rendering state is a more opaque state and the second rendering state is a less opaque state that is less opaque than the more opaque state. In some examples, the plurality of replaced strut graphical representations and the plurality of replacement strut graphical representations have linear rates of change between the first rendering state and the second rendering state. In some examples, the plurality of fixator graphical representations include one or more intermediate fixator graphical representations that represent the fixator at one or more intermediate stages between the swap start stage and a swap end stage, and the one or more intermediate fixator graphical representations may be rendered according to the linear rates of change. In this manner, the plurality of replaced strut graphical representations may gradually fade out from the swap start stage to the swap end stage, and the plurality of replacement strut graphical representations may gradually fade in from the swap start stage to the swap end stage.

In some examples, a treatment plan including at least one interfamily strut swap may be generated for manipulating a fixator including rings and struts to correct a deformity of first and second anatomical structure segments. A computing system may determine positions and orientations of the first and the second anatomical structure segments in three-dimensional space. The computing system may then determine manipulations to the fixator for correction of the deformity. The manipulations may include a plurality of adjustments to strut lengths and an interfamily strut swap between a first strut in a first strut family and a second strut in a second strut family. The computing system may then provide, to one or more users, indications of the manipulations to the fixator. The first strut family may include a first plurality of struts having different size ranges with respect to one another. The second strut family may include a second plurality of struts having different size ranges with respect to one another. In some examples, the first strut family may be a standard strut family and the second strut family may be a quick adjust strut family (or vice versa). In some examples, a first maximum length of a longest strut in the first strut family may be longer than a second maximum length of a longest strut in the second strut family. In some examples, a first minimum length of a shortest strut in the first strut family may be shorter than a second minimum length of a shortest strut in the second strut family. In some examples, an inclusion of the interfamily strut swap in the manipulations may be based on a determination that the correction of the deformity cannot be performed using struts from only a single strut family. In some examples, the manipulations may be determined based at least in part on a rule to select a treatment plan with a fewest amount of strut swaps from a plurality of available treatment plans. In some examples, the manipulations may be determined based at least in part on a rule to select a treatment plan with at least one strut swap having at least a minimum strut swap duration from a plurality of available treatment plans.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

The foregoing summary, as well as the following detailed description of the preferred embodiments of the application, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the methods and/or techniques of orthopedic fixation with imagery analysis, there are shown in the drawings preferred embodiments. It should be understood, however, that the instant application is not limited to the precise arrangements and/or instrumentalities illustrated in the drawings, in which:

FIG. 1 is a perspective view of a fixation assembly positioned for imaging in accordance with an embodiment;

FIG. 2 is a perspective view of an example imaging process of the fixation assembly illustrated in FIG. 1 ;

FIGS. 3A and 3B are flow diagrams illustrating an example process for controlling manipulation of a fixation apparatus to correct an anatomical structure deformity;

FIG. 4 is a screen shot of an example interface for selecting a Perspective Frame Matching (PFM) technique;

FIG. 5 is a screen shot of an example configuration information entry interface for the PFM technique;

FIG. 6 is a screen shot of an example first image information entry interface for the PFM technique;

FIG. 7 is a screen shot of an example close-up assist interface for the PFM technique;

FIGS. 8A-8H are screen shots of an example second image information entry interface for the PFM technique;

FIG. 9 is a screen shot of example deformity parameter interface for the PFM technique;

FIG. 10 is a screen shot of an example mounting parameter interface for the PFM technique;

FIG. 11 is a screen shot of a first example treatment plan interface for the PFM technique;

FIG. 12 is a screen shot of a second example treatment plan interface for the PFM technique;

FIG. 13 is a screen shot of a third example treatment plan interface for the PFM technique;

FIG. 14 is a flow diagram illustrating an example process for providing a plurality of fixator graphical representations including graphical strut swap range indications;

FIG. 15 is a diagram illustrating an example fixator graphical representation prior to a strut swap range;

FIG. 16 is a diagram illustrating an example fixator graphical representation at a start stage of a strut swap range;

FIG. 17 is a diagram illustrating example fixator graphical representation at an intermediate stage of a strut swap range;

FIG. 18 is a flow diagram illustrating an example fixator graphical representation at a midpoint stage of a strut swap range;

FIG. 19 is a diagram illustrating example fixator graphical representation at another intermediate stage of a strut swap range;

FIG. 20 is a diagram illustrating an example fixator graphical representation at an end stage of a strut swap range;

FIG. 21 is a diagram illustrating an example fixator graphical representation subsequent to a strut swap range;

FIG. 22 is a flow diagram illustrating an example process for generating a treatment plan including an interfamily strut swap;

FIG. 23 is a block diagram of an example computing device for use in accordance with the present disclosure.

DETAILED DESCRIPTION

For convenience, the same or equivalent elements in the various embodiments illustrated in the drawings have been identified with the same reference numerals. Certain terminology is used in the following description for convenience only and is not limiting. The words “right”, “left”, “top” and “bottom” designate directions in the drawings to which reference is made. The words “inward”, “inwardly”, “outward”, and “outwardly” refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. The terminology intended to be non-limiting includes the above-listed words, derivatives thereof and words of similar import.

Referring initially to FIG. 1 , bodily tissues, for instance first and second anatomical structure segments 102, 104, can be aligned and/or oriented to promote union or other healing between the bodily tissues. Anatomical structures may include, for example, anatomical tissue and artificial anatomical implants. Anatomical tissue may include, for example, bone or other tissue in the body. The alignment and/or orientation of the bodily tissues can be achieved by connecting the bodily tissues to an adjustable fixation apparatus, such as orthopedic fixator 100. The orthopedic fixator can comprise an external fixation apparatus that includes a plurality of discrete fixator members that remain external to the patient's body, but that are attached to respective discreet bodily tissues, for example with minimally invasive attachment members. A fixation apparatus may include, for example, a distraction osteogenesis ring system, a hexapod, or a Taylor spatial frame. By adjusting the spatial positioning of the fixator members with respect to each other, the respective bodily tissues attached thereto can be reoriented and/or otherwise brought into alignment with each other, for example to promote union between the bodily tissues during the healing process. The use of external orthopedic fixators in combination with the imagery analysis and positioning techniques described herein can be advantageous in applications where direct measurement and manipulation of the bodily tissues is not possible, where limited or minimally invasive access to the bodily tissues is desired, or the like. Some examples of orthopedic fixators and their use for correcting deformities of anatomical structure segments, as well as techniques for performing imagery analysis on the fixators and anatomical structure segments are described in U.S. Pat. No. 9,642,649, entitled “ORTHOPEDIC FIXATION WITH IMAGERY ANALYSIS,” issued on May 9, 2017, the entirety of which is hereby incorporated by reference.

The fixator members can be connected to each other via adjustment members, the adjustment members configured to facilitate the spatial repositioning of the fixator members with respect to each other. For example, in the illustrated embodiment, the orthopedic fixator 100 comprises a pair of fixator members in the form of an upper fixator ring 106 and a lower fixator ring 108. The fixator rings 106, 108 can be constructed the same or differently. For instance, the fixator rings 106, 108 can have diameters that are the same or different. Similarly, the fixator rings 106, 108 can be constructed with varying cross sectional diameters, thicknesses, etc. It should be appreciated that the fixator members of the orthopedic fixator 100 are not limited to the illustrated upper and lower fixator rings 106, 108, and that the orthopedic fixator 100 can be alternatively constructed. For example, additional fixator rings can be provided and interconnected with the fixator ring 106 and/or 108. It should further be appreciated that the geometries of the fixator members are not limited to rings, and that at least one, such as all of the fixator members can be alternatively constructed using any other suitable geometry.

The first and second anatomical structure segments 102, 104 can be rigidly attached to the upper and lower fixator rings 106, 108, respectively, with attachment members that can be mounted to the fixator rings 106, 108. For example, in the illustrated embodiment, attachment members are provided in the form of attachment rods 110 and attachment wires 112.

The rods 110 and the wires 112 extend between proximal ends attached to mounting members 114 that are mounted to the fixator rings 106, 108, and opposed distal ends that are inserted into or otherwise secured to the anatomical structure segments 102, 104. The mounting members 114 can be removably mounted to the fixator rings 106, 108 at predefined points along the peripheries of the fixator rings 106, 108, for example by disposing them into threaded apertures defined by the fixator rings. With respect to each fixator ring 106, 108, the mounting members 114 can be mounted to the upper surface of the ring, the lower surface of the ring, or any combination thereof. It should be appreciated that the attachment members are not limited to the configuration of the illustrated embodiment. For example, any number of attachment members, such as the illustrated rods 110 and wires 112 and any others, can be used to secure the anatomical structure segments to respective fixator members as desired. It should further be appreciated that one or more of the attachment members, for instance the rods 110 and/or wires 112, can be alternatively configured to mount directly to the fixator rings 106, 108, without utilizing mounting members 114.

The upper and lower fixator rings 106, 108 can be connected to each other by at least one, such as a plurality of adjustment members. At least one, such as all, of the adjustment members can be configured to allow the spatial positioning of the fixator rings with respect to each other to be adjusted. For example, in the illustrated embodiment, the upper and lower fixator rings 106, 108 are connected to each other with a plurality of adjustment members provided in the form of adjustable length struts 116. It should be appreciated that the construction of the orthopedic fixator 100 is not limited to the six struts 116 of the illustrated embodiment, and that more or fewer struts can be used as desired.

Each of the adjustable length struts 116 can comprise opposed upper and lower strut arms 118, 120. Each of the upper and lower strut arms 118, 120 have proximal ends disposed in a coupling member, or sleeve 122, and opposed distal ends that are coupled to universal joints 124 mounted to the upper and lower fixator rings 106, 108, respectively. The universal joints of the illustrated embodiment are disposed in pairs spaced evenly around the peripheries of the upper and lower fixator rings 106, 108, but can be alternatively placed in any other locations on the fixator rings as desired.

The proximal ends of the upper and lower strut arms 118, 120 of each strut 116 can have threads defined thereon that are configured to be received by complementary threads defined in the sleeve 122, such that when the proximal ends of the upper and lower strut arms 118, 120 of a strut 116 are received in a respective sleeve 122, rotation of the sleeve 122 causes the upper and lower strut arms 118, 120 to translate within the sleeve 122, thus causing the strut 116 to be elongated or shortened, depending on the direction of rotation. Thus, the length of each strut 116 can be independently adjusted with respect to the remaining struts. It should be appreciated that the adjustment members are not limited to the length adjustable struts 116 of the illustrated embodiment, and that the adjustment members can be alternatively constructed as desired, for example using one or more alternative geometries, alternative length adjustment mechanisms, and the like.

The adjustable length struts 116 and the universal joints 124 by which they are mounted to the upper and lower fixator rings 106, 108, allow the orthopedic fixator 100 to function much like a Stewart platform, and more specifically like a distraction osteogenesis ring system, a hexapod, or a Taylor spatial frame. That is, by making length adjustments to the struts 116, the spatial positioning of the upper and lower fixator rings 106, 108, and thus the anatomical structure segments 102, 104 can be altered. For example, in the illustrated embodiment the first anatomical structure segment 102 is attached to the upper fixator ring 106 and the second anatomical structure segment 104 is attached to the lower fixator ring 108. It should be appreciated that attachment of the first and second anatomical structure segments 102, 104 to the upper and lower fixator rings 106, 108 is not limited to the illustrated embodiment (e.g., where the central longitudinal axes L1, L2 of the first and second anatomical structure segments 102, 104 are substantially perpendicular to the respective planes of the upper and lower fixator rings 106, 108), and that a surgeon has complete flexibility in aligning the first and second anatomical structure segments 102, 104 within the upper and lower fixator rings 106, 108 when configuring the orthopedic fixator 100.

By varying the length of one or more of the struts 116, the upper and lower fixator rings 106, 108, and thus the anatomical structure segments 102 and 104 can be repositioned with respect to each other such that their respective longitudinal axes L1, L2 are substantially aligned with each other, and such that their respective fractured ends 103, 105 abut each other, so as to promote union during the healing process. It should be appreciated that adjustment of the struts 116 is not limited to the length adjustments as described herein, and that the struts 116 can be differently adjusted as desired. It should further be appreciated that adjusting the positions of the fixator members is not limited to adjusting the lengths of the length adjustable struts 116, and that the positioning of the fixator members with respect to each other can be alternatively adjusted, for example in accordance the type and/or number of adjustment members connected to the fixation apparatus.

Repositioning of the fixator members of an orthopedic fixation apparatus, such as orthopedic fixator 100, can be used to correct displacements of angulation, translation, rotation, or any combination thereof, within bodily tissues. A fixation apparatus, such as orthopedic fixator 100, utilized with the techniques described herein, can correct a plurality of such displacement defects individually or simultaneously. However, it should be appreciated that the fixation apparatus is not limited to the illustrated orthopedic fixator 100, and that the fixation apparatus can be alternatively constructed as desired. For example, the fixation apparatus can include additional fixation members, can include fixation members having alternative geometries, can include more or fewer adjustment members, can include alternatively constructed adjustment members, or any combination thereof.

Referring now to FIG. 2 , an example imaging of a fixation apparatus will now be described in detail. The images can be captured using the same or different imaging techniques. For example, the images can be acquired using x-ray imaging, computer tomography, magnetic resonance imaging, ultrasound, infrared imaging, photography, fluoroscopy, visual spectrum imaging, or any combination thereof.

The images can be captured from any position and/or orientation with respect to each other and with respect to the fixator 100 and the anatomical structure segments 102, 104. In other words, there is no requirement that the captured images be orthogonal with respect to each other or aligned with anatomical axes of the patient, thereby providing a surgeon with near complete flexibility in positioning the imagers 130. Preferably, the images 126, 128 are captured from different directions, or orientations, such that the images do not overlap. For example, in the illustrated embodiment, the image planes of the pair of images 126, 128 are not perpendicular with respect to each other. In other words, the angle α between the image planes of the images 126, 128 is not equal to 90 degrees, such that the images 126, 128 are non-orthogonal with respect to each other. Preferably, at least two images are taken, although capturing additional images may increase the accuracy of the method.

The images 126, 128 can be captured using one or more imaging sources, or imagers, for instance the x-ray imagers 130 and/or corresponding image capturing devices 127, 129. The images 126, 128 can be x-ray images captured by a single repositionable x-ray imager 130, or can be captured by separately positioned imagers 130. Preferably, the position of the image capturing devices 127, 129 and/or the imagers 130 with respect to the space origin 135 of the three-dimensional space, described in more detail below, are known. The imagers 130 can be manually positioned and/or oriented under the control of a surgeon, automatically positioned, for instance by a software assisted imager, or any combination thereof. The fixator 100 may also have a respective fixator origin 145.

Referring now to FIGS. 3A and 3B, an example process for controlling manipulation of a fixation apparatus including rings and struts to correct an anatomical structure deformity of first and second anatomical structure segments will now be described in detail. In particular, at operation 310, first and second anatomical structure segments are attached to a fixation apparatus, for example as shown in FIG. 1 and described in detail above. At operation, 312, first and second images of the fixation apparatus and the attached first and second anatomical structure segments are captured, for example as shown in FIG. 2 and described in detail above.

The remaining operations of the process of FIGS. 3A and 3B (e.g., operations 314-342) will now be described in association with a treatment technique referred to hereinafter as Perspective Frame Matching, in which images, such as post-operative x-rays, may be used along with a frame to generate deformity and mounting parameters for a strut adjustment plan. For example, referring now to FIG. 4 , an example treatment planning technique selection interface 400-A is shown. In the example of FIG. 4 , the user has selected option 401 in order to use the Perspective Frame Matching (PFM) technique, which will now be described in detail with reference to FIGS. 5-13 .

Referring back to FIG. 3A, at operation 314, configuration information associated with a fixation apparatus is received, for example using one or more graphical user interfaces of a computing system. In some examples, the configuration information may include one or more geometric characteristics (e.g., size, length, diameter, etc.) of one or more elements of the fixation apparatus, such as struts, hinges, rings, and others. In some examples, the configuration information may include information such as ring types (e.g., full ring, foot plate, etc.), indications of mounting points (e.g., ring holes) used for strut mounting, and other information. In some examples, the configuration information may also include information about marker elements, for example that are mounted to components of the fixation apparatus, such as struts, hinges, and rings. Referring now to FIG. 5 , an example configuration information entry interface 500 is shown. As shown, interface 500 includes ring type indicators 501 and 502, which, in this example, are drop down menus that may be used to select ring types for the proximal and distal rings, respectively. Indicators 501 and 502 are set to the “Full” option to indicate that the proximal and distal rings are full rings. Interface 500 also includes diameter indicators 503 and 504, which, in this example, are drop down menus that may be used to select diameters or lengths for the proximal and distal rings, respectively.

The interface 500 also includes controls for entry of strut information. In particular, interface 500 includes six drop down menus 512 may each be used to indicate a size of a respective strut. Global strut size indicator 511 may also be used to globally select a size for all six struts. Length selectors 513 may be each be used to select a length of a respective strut. Length indicators 514 may be each be used to provide a visual representation of the lengths of the respective struts. It is noted that the length indicators 514 do not necessarily depict the actual exact length of each strut, but rather represent the comparative lengths of the struts with respect to one another.

Save and Update button 516 may be selected to save and update the configuration information values shown in interface 500. In some examples, selection of button 516 may cause interface 500 to display and/or update a graphical representation 520 of the fixation apparatus generated based, at least in part, on the entered configuration information. The graphical representation 520 may be displayed using one or more graphical user interfaces of a computing system. As shown, graphical representation 520 includes six struts that may be color-coded in multiple colors for easy identification. For example, in some cases, each of the struts (or at least two of the struts) may be shown in different colors with respect to one another. The struts in graphical representation 520 may have sizes, lengths, mounting points, and other features corresponding to entered configuration information. Graphical representation 520 also depicts the fixator rings, which may have diameters/lengths, ring types, and other features corresponding to entered configuration information. Graphical representation 520 may, for example, improve efficiency and reliability by providing the user with a visual confirmation of information entered into interface 500, for example to allow fast and easy identification of errors or other problems.

At operation 316, images of the fixation apparatus and the first and second anatomical structure segments attached thereto are displayed, for example using one or more graphical user interfaces of a computing system. The displayed images may include images that were captured at operation 312, such as using x-ray imaging, computer tomography, magnetic resonance imaging, ultrasound, infrared imaging, photography, fluoroscopy, visual spectrum imaging, or any combination thereof. Techniques for acquiring images of the fixation apparatus and the first and second anatomical structure segments are described in detail above and are not repeated here. As set forth above, the acquired and displayed images need not necessarily be orthogonal to one another. Referring now to FIG. 6 , an example first image information entry interface 600 is shown. As shown, interface 600 includes images 601-A and 601-B, which show the fixation apparatus and first and second anatomical structure segments from different angles. In the example of FIG. 6 , image 601-A corresponds to an anteroposterior (AP) View, while image 601-B corresponds to a lateral (LAT) view. In some examples, the displayed images 601-A-B may be loaded and saved in computer memory, for example in a library, database or other local collection of stored images. The displayed images 601-A-B may then be selected and retrieved, acquired, and/or received from memory for display.

At operation 318, first image information is received, for example using one or more graphical user interfaces of a computing system. The first image information may include indications of one or more locations, within the images, of at least part of one or more elements of the fixation apparatus. For example, the first image information may include one or more indications of locations of struts, hinges, rings, and other fixator elements. In some examples, the first image information may also include information about locations, within the images, of marker elements, for example that are mounted to components of the fixation apparatus, such as struts, hinges, and rings. In some cases, the first image information may include points representing locations of hinges and/or lines or vectors representing locations of struts. In some examples, the first image information may be entered into a computing system by selecting or indicating one or more locations within the displayed images, for example using a mouse, keyboard, touchscreen or other user input devices. In particular, using one or more input devices, a user may select points or other locations in the images, draw lines, circles, and generate other graphical indications within the images. For example, in some cases, a user may generate a point or small circle at a particular location in an image to indicate a location (e.g., center point) of a hinge within the image. As another example, in some cases, a user may generate a line and/or vector within an image to indicate a location and/or length of a strut within the image.

For example, as shown in FIG. 6 , interface 600 includes six AP View strut indicator buttons 611-A corresponding to each of the six struts of the fixation apparatus shown in AP View image 601-A. Each button 611-A includes text indicating a respective strut number (i.e., Strut 1, Strut 2, Strut 3, Strut 4, Strut 5, Strut 6). Buttons 611-A may be selected by a user to indicate a strut for which first image information (e.g., hinge locations, strut locations, etc.) will be provided by the user in AP View image 601-A. For example, in some cases, to provide first image information for Strut 1 in AP View image 601-A, a user may first select the top strut indicator button 611-A (labeled with the text “Strut 1”) in order to indicate to the software that the user is about to provide first image information for Strut 1 within AP View image 601-A. In some cases, the strut indicator button 611-A for Strut 1 may be pre-selected automatically for the user. Upon selection (or automatic pre-selection) of the strut indicator button 611-A for Strut 1, the user may proceed to draw (or otherwise indicate) a representation of Strut 1 within AP View image 601-A. For example, in some cases, the user may use a mouse or other input device to select a location 621 (e.g., a center point) of a proximal hinge for Strut 1 within image 601-A. In some examples, the user may then use a mouse or other input device to select a location 622 (e.g., a center point) of the distal hinge of Strut 1 within image 601-A. In some examples, the user may indicate the location and/or length of Strut 1 by selecting the locations of the proximal and distal hinges and/or as the endpoints of a line or vector that represents the location and/or length of Strut 1. For example, as shown in FIG. 6 , the software may generate points or circles at the locations 621 and 622 of the proximal and distal hinges selected by the user within image 601-A. Additionally, the software may generate a line 623 representing the location and/or length of Strut 1 that connects the points or circles at the locations 621 and 622 and of the proximal and distal hinges selected by the user within image 601-A. Any other appropriate input techniques may also be employed by the user to indicate a location and/or length of Strut 1 within image 610-A, such as generating line 623 by dragging and dropping a mouse, using a finger and/or pen on a touch screen, keyboard, and others. In some examples, the above described process may be repeated to draw points representing proximal and distal hinges and lines representing the locations and/or lengths of each of the six struts in the AP View image 601-A. Furthermore, the above described process may also be repeated using LAT View strut indicator buttons 611-B to draw points representing proximal and distal hinges and lines representing the locations and/or lengths of each of the six struts in the LAT View image 601-B.

In some examples, the first image information generated within images 601-A and 601-B may include color-coded graphical representations of the struts, for example to enable the graphical representations to be more clearly associated with their respective struts. For example, in FIG. 6 , the graphical representations (e.g., points, circles, and/or lines) of Strut 1 in images 601A- and 601-B may be colored in red. This may match a strut icon (which may also be colored red) displayed in the strut indicator buttons 611-A and 611-B for Strut 1 (displayed to the right of the text “Strut 1” in buttons 611-A and 611-B). As another example, in FIG. 6 , the graphical representations (e.g., points, circles, and/or lines) of Strut 3 in images 601-A and 601-B may be colored in yellow. This may match a strut icon (which may also be colored yellow) displayed in the strut indicator buttons 611-A and 611-B for Strut 3 (displayed to the right of the text “Strut 3” in buttons 611-A and 611-B).

FIG. 6 includes an AP View close-up assist checkbox 616-A and a LAT View close-up assist checkbox 616-B, for example provided using one or more graphical interfaces of a computing system. Selection of checkboxes 616-A and 616-B may allow close-up views of areas of images 601-A and 601-B surrounding the proximal and distal hinges of the struts that are currently being drawn by the user. This may enable more accurate indications of the locations (e.g., center points) of the hinges. Referring now to FIG. 7 , close-up assist interface 700 depicts another AP View image 701 with the close-up assist being selected to provide a proximal hinge close-up assist view 702 and a distal hinge close-up assist view 703. As shown, proximal hinge close-up assist view 702 provides an enlarged view of an area of AP View image 701 associated with the proximal hinge, while distal hinge close-up assist view 703 provides an enlarged view of an area of AP View image 701 associated with the distal hinge. The user may manipulate (e.g., drag and drop) the location of the point/circle 721 in proximal hinge close-up assist view 702 in order to more accurately depict the center point of the proximal hinge. The user may also manipulate (e.g., drag and drop) the location of the point/circle 722 in distal hinge close-up assist view 703 in order to more accurately depict the center point of the distal hinge. As should be appreciated, corresponding close-up assist views similar to views 702 and 703 may also be provided for a respective LAT View image, for example using one or more graphical interfaces of a computing system.

Referring back to FIG. 6 , to the right of buttons 611-A, are six proximal hinge selector buttons 612-A. Additionally, to the right of buttons 612-A, are six distal hinge selector buttons 613-A. Furthermore, to the right of buttons 613-A, are six strut line selector buttons 614-A. In some examples, buttons 612-A and/or 613-A may be selected to use the locations (e.g., center points) of the proximal and/or distal hinges indicated in AP View image 601-A in calculating positions and orientations of the first and the second anatomical structure segments and rings of the fixation apparatus in three-dimensional space (see operation 322). Additionally, in some examples, buttons 612-A and/or 613-A may be selected to use the lines or vectors representing the location and/or length of struts indicated in AP View image 601-A in calculating positions and orientations of the first and the second anatomical structure segments in three-dimensional space. Similarly, buttons 612-B, 613-B, and 614-B may be used to select the use of locations (e.g., center points) of the proximal and/or distal hinges or strut lines or vectors indicated in LAT View image 601-B in calculating positions and orientations of the first and the second anatomical structure segments in three-dimensional space.

Referring again to FIG. 3A, at operation 320, second image information is received, for example using one or more graphical user interfaces of a computing system. The second image information may include indications of one or more locations, within the images, of at least part of the first and the second anatomical structure segments. In some examples, the second image information may include indications of center lines of the first and the second anatomical structure segments and/or one or more reference points (e.g., end points) of the first and the second anatomical structure segments. In some examples, the second image information may also include indications of locations of marker elements, for example implanted or otherwise associated with the first and the second anatomical structure segments. In some examples, the second image information may be entered into a computing system by selecting or indicating one or more locations within the displayed images, for example using a mouse, keyboard, touchscreen or other user input devices. In particular, using one or more input devices, a user may select points or other locations in the images, draw lines, circles, and generate other graphical indications within the images. For example, in some cases, a user may generate points or small circles at particular locations in an image to indicate one or more reference points (e.g., end points) of the first and the second anatomical structure segments within the images. As another example, in some cases, a user may generate a line within an image to indicate a center line of the first and the second anatomical structure segments within the images.

Referring now to FIG. 8A, an example second image information entry interface 800 is shown. As shown, interface 800 includes AP View image 601-A and LAT View image 601-B. Additionally, interface 800 includes buttons 801-808, which may be used to assist in indication of anatomical structure center lines and reference points as will be described below. In particular, buttons 801 and 805 may be selected to indicate a proximal anatomical structure reference point in the AP View and LAT View, respectively. Buttons 802 and 806 may be selected to indicate a distal anatomical structure reference point in the AP View and LAT View, respectively. Buttons 803 and 807 may be selected to indicate a proximal anatomical structure center line in the AP View and LAT View, respectively. Buttons 804 and 808 may be selected to indicate a distal anatomical structure center line in the AP View and LAT View, respectively. For example, as shown in FIG. 8A, a user may select button 807 and then use one or more input devices to draw the center line 831 for the proximal anatomical structure within LAT View image 601-B. In some examples, the center line 831 may be colored red. Additionally, two guidelines 832 are generated and displayed by the software on both sides of the red center line. In some examples, the guidelines 832 may be colored green. These guidelines 832 may be displayed while the user is drawing the center line 831 in order to assist the user in locating the center of the anatomical structure segment. The guidelines 832 may be generated at equal distances from each side of the center line 831 and may assist the user by, for example, potentially allowing the user to match (or nearly match) the guidelines 832 to sides of the anatomical structure segment. As shown in FIG. 8B, the user may select button 808 and then use one or more input devices to draw the center line 841 for the distal anatomical structure within LAT View image 601-B. As shown in FIG. 8C, the user may select button 803 and then use one or more input devices to draw the center line 851 for the proximal anatomical structure within AP View image 601-A. As shown in FIG. 8D, the user may select button 804 and then use one or more input devices to draw the center line 861 for the distal anatomical structure within AP View image 601-A. As shown in FIGS. 8B-8D, guidelines 832 may also be displayed for assistance in drawing center lines 841, 851 and 861.

As shown in FIG. 8E, the user may select button 805 and then use one or more input devices to indicate a reference point (e.g., end point) for the proximal anatomical structure within LAT View image 601-B. As shown, a user has indicated a reference point 811 in LAT View image 601-B at an end point of the proximal anatomical structure segment. Additionally, upon indication of reference point 811, the software may generate and display a corresponding dashed reference line 812 in AP View image 601-A. The reference line 812 is a line drawn across AP View image 601-A that passes through the location of the LAT View proximal reference point 811 within AP View image 601-A. The reference line 812 may, therefore, assist the user in determining the location of the corresponding AP View proximal reference point, which may often be at the intersection of the reference line 812 and the AP View proximal center line 851 within the AP View image 601-A. As shown in FIG. 8F, the user may select button 801 and then use one or more input devices to indicate a reference point (e.g., end point) for the proximal anatomical structure within AP View image 601-A. In this example, the AP View proximal anatomical structure reference point 814 is indicated at the intersection of reference line 812 and the AP View proximal center line 851 within the AP View image 601-A. The software may then generate and display a corresponding dashed reference line 813 in the LAT View image 601-B. The reference line 813 is a line drawn across LAT View image 601-B that passes through the location of the AP View proximal reference point 814 within LAT View image 601-B. The reference line 813 may assist the user by helping the user to confirm that the AP View reference point 814 was placed correctly by showing how well it lines up relative to the LAT View reference point 811.

As shown in FIG. 8G, the user may select button 806 and then use one or more input devices to indicate a reference point (e.g., end point) for the distal anatomical structure within LAT View image 601-B. As shown, a user has indicated a reference point 815 in LAT View image 601-B at an end point of the distal anatomical structure segment. Additionally, upon indication of reference point 815, the software may generate and display a corresponding dashed reference line 816 in AP View image 601-A. The reference line 816 is a line drawn across AP View image 601-A that passes through the location of the LAT View distal reference point 815 within AP View image 601-A. The reference line 816 may, therefore, assist the user in determining the location of the corresponding AP View distal reference point, which may often be at the intersection of the reference line 816 and the AP View distal center line within the AP View image 601-A. As shown in FIG. 8H, the user may select button 802 and then use one or more input devices to indicate a reference point (e.g., end point) for the distal anatomical structure within AP View image 601-A. In this example, the AP View distal anatomical structure reference point 817 is indicated at the intersection of reference line 816 and the AP View distal center line within the AP View image 601-A. The software may then generate and display a corresponding dashed reference line 818 in the LAT View image 601-B. The reference line 818 is a line drawn across LAT View image 601-B that passes through the location of the AP View distal reference point 817 within LAT View image 601-B. The reference line 818 may assist the user by helping the user to confirm that the AP View reference point 817 was placed correctly by showing how well it lines up relative to the LAT View reference point 815.

Referring again to FIG. 3A, at operation 322, positions and orientations of the first and second anatomical structure segments and rings of the fixation apparatus are determined in three-dimensional space. For example, in some cases, imaging scene parameters pertaining to fixator 100, the anatomical structure segments 102, 104, imager(s) 130, and image capturing devices 127, 129 are obtained. The imaging scene parameters can be used in constructing a three-dimensional representation of the positioning of the anatomical structure segments 102, 104 in the fixator 100, as described in more detail below. One or more of the imaging scene parameters may be known. Imaging scene parameters that are not known can be obtained, for example by mathematically comparing the locations of fixator element representations in the two-dimensional space of the x-ray images 126, 128 to the three-dimensional locations of those elements on the geometry of the fixator 100. In a preferred embodiment, imaging scene parameters can be calculated using a pin hole or perspective camera models. For example, the imaging scene parameters can be determined numerically using matrix algebra, as described in more detail below.

The imaging scene parameters can include, but are not limited to image pixel scale factors, image pixel aspect ratio, the image sensor skew factor, the image size, the focal length, the position and orientation of the imaging source, the position of the principle point (defined as the point in the plane of a respective image 126, 128 that is closest to the respective imager 130), positions and orientations of elements of the fixator 100, the position and orientation of a respective image receiver, and the position and orientation of the imaging source's lens.

In a preferred embodiment, at least some, such as all of the imaging scene parameters can be obtained by comparing the locations of representations of particular components, or fixator elements of the fixator 100 within the two-dimensional spaces of the images 126, 128, with the corresponding locations of those same fixator elements in actual, three-dimensional space. The fixator elements comprise components of the orthopedic fixator 100, and preferably are components that are easy to identify in the images 126, 128. Points, lines, conics, or the like, or any combination thereof can be used to describe the respective geometries of the fixator elements. For example, the representations of fixator elements used in the comparison could include center lines of one or more of the adjustable length struts 116, center points of the universal joints 124, center points of the mounting members 114, and the like.

The fixator elements can further include marker elements that are distinct from the above-described components of the fixator 100. The marker elements can be used in the comparison, as a supplement to or in lieu of using components of the fixator 100. The marker elements can be mounted to specific locations of components of the fixator 100 prior to imaging, can be imbedded within components of the fixator 100, or any combination thereof. The marker elements can be configured for enhanced viewability in the images 126, 128 when compared to the viewability of the other components of the fixator 100. For example, the marker elements may be constructed of a different material, such as a radio-opaque material, or may be constructed with geometries that readily distinguish them from other components of the fixator 100 in the images 126, 128. In an example embodiment, the marker elements can have designated geometries that correspond to their respective locations on the fixator 100.

Fixator elements can be identified for use in the comparison. For example, locations, within the images 126, 128 of fixator elements may be indicated using the first image information received at operation 318 and described in detail above. In some examples, the locations of the fixator elements in the two-dimensional space of the images 126, 128 may be determined with respect to local origins 125 defined in the imaging planes of the images 126, 128. The local origins 125 serve as a “zero points” for determining the locations of the fixator elements in the images 126, 128. The locations of the fixator elements can be defined by their respective x and y coordinates with respect to a respective local origin 125. The location of the local origin 125 within the respective image can be arbitrary so long it is in the plane of the image. Typically, the origin is located at the center of the image or at a corner of the image, such as the lower left hand corner. It should be appreciated that the locations of the local origins are not limited to illustrated local origins 125, and that the local origins 125 can be alternatively defined at any other locations.

In some examples, a respective transformation matrix P may then be computed for each of the images 126, 128. The transformation matrices can be utilized to map location coordinates of one or more respective fixator elements in actual three-dimensional space to corresponding location coordinates of the fixator element(s) in the two-dimensional space of the respective image 126, 128. It should be appreciated that the same fixator element(s) need not be used in the comparisons of both images 126, 128. For example, a fixator element used in constructing the transformation matrix associated with image 126 can be the same or different from the fixator element used in constructing the transformation matrix associated with image 128. It should further be appreciated that increasing the number of fixator elements used in computing the transformation matrices can increase the accuracy method. The following equation represents this operation:

$\begin{matrix} {\begin{bmatrix} x \\ y \\ 1 \end{bmatrix} = {P \cdot \begin{bmatrix} X \\ Y \\ Z \\ 1 \end{bmatrix}}} & (1) \end{matrix}$

The symbols x and y represent location coordinates, with respect to the local origin 125, of a fixator element point in the two-dimensional space of images 126, 128. The symbols X, Y and Z represent corresponding location coordinates, with respect to a space origin 135, of the fixator element point in actual three-dimensional space. In the illustrated embodiment, the point corresponding to the center of the plane defined by the upper surface of the upper fixator ring 106 has been designated as the space origin 135. The illustrated matrix P can be at least four elements wide and three elements tall. In a preferred embodiment, the elements of the matrix P can be computed by solving the following matrix equation:

A·p=B  (2)

The vector p can contain eleven elements representing values of the matrix P. The following equations present arrangements of the elements in the vector p and the matrix P:

$\begin{matrix} {p = \left\lbrack {p_{1}p_{2}p_{3}p_{4}p_{5}p_{6}p_{7}p_{8}p_{9}p_{10}p_{11}} \right\rbrack^{T}} & (3) \end{matrix}$ $\begin{matrix} {P = \begin{bmatrix} p_{1} & p_{2} & p_{3} & p_{4} \\ p_{5} & p_{6} & p_{7} & p_{8} \\ p_{9} & p_{10} & p_{11} & p_{12} \end{bmatrix}} & (4) \end{matrix}$

In the preferred embodiment, the twelfth element p₁₂ of the matrix P can be set to a numerical value of one. The matrices A and B can be assembled using the two-dimensional and three-dimensional information of the fixator elements. For every point representing a respective fixator element, two rows of matrices A and B can be constructed. The following equation presents the values of the two rows added to the matrices A and B for every point of a fixator element (e.g., a center point of a respective universal joint 124):

$\begin{matrix} {{\begin{bmatrix} \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots \\ X & Y & Z & 1 & 0 & 0 & 0 & 0 & {{- x} \cdot X} & {{- x} \cdot Y} & {{- x} \cdot Z} \\ 0 & 0 & 0 & 0 & X & Y & Z & 1 & {{- y} \cdot X} & {{- y} \cdot Y} & {{- y} \cdot Z} \\ \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots \end{bmatrix} \cdot P} = \begin{bmatrix} \ldots \\ x \\ y \\ \ldots \end{bmatrix}} & (5) \end{matrix}$

The symbols X, Y and Z represent location coordinate values of a fixator element point in actual three-dimensional space relative to the space origin 135, and the symbols x and y represent location coordinate values of the corresponding fixator element point in the two-dimensional space of the respective image 126, 128 relative to local origin 125.

For every line representing a respective fixator element, two rows of matrices A and B can be constructed. The following equation presents the values of the two rows added to the matrices A and B for every line of a fixator element (e.g., a center line of a respective adjustable length strut 116):

$\begin{matrix} {\begin{bmatrix} \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots \\ {X \cdot a} & {Y \cdot a} & {Z \cdot a} & a & {X \cdot b} & {Y \cdot b} & {Z \cdot b} & b & {X \cdot c} & {Y \cdot c} & {Z \cdot c} \\ {{dX} \cdot a} & {{dY} \cdot a} & {{dZ} \cdot a} & 0 & {{dX} \cdot b} & {{dY} \cdot b} & {{dZ} \cdot b} & 0 & {{dY} \cdot c} & {{dY} \cdot c} & {{dZ} \cdot c} \\ \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots & \ldots \end{bmatrix} \cdot {p\begin{bmatrix} \ldots \\ {- c} \\ 0 \\ \ldots \end{bmatrix}}} & (6) \end{matrix}$

The symbols X, Y and Z represent location coordinate values of a point belonging to a line of a fixator element in actual three-dimensional space relative to the space origin 135. The symbols dX, dY and dZ represent gradient values of the line in actual three-dimensional space. The symbols a, b and c represent constants defining a line in the two-dimensional space of a respective image 126, 128. For example, a, b, and c can be computed using two points belonging to a line on a respective image 126, 128. In a preferred embodiment, the value of b is assumed to be 1, unless the line is a vertical line, in which case the value of b is zero. A correlation of constants a, b and c with the respective image coordinates x and y is presented in the following equation:

a·x+b·y+c=0  (7)

The equation (2) can be over constrained by using six or more fixator elements, for example the adjustable length struts 116. It should be appreciated that it is not necessary for all of the fixator elements to be visible in a single one of the images 126, 128 in order to obtain the matrix P. It should further be appreciated that if one or more of the above-described imaging scene parameters are known, the known parameters can be used to reduce the minimum number of the fixator elements required to constrain equation (2). For instance, such information could be obtained from modern imaging systems in DICOM image headers. Preferably, a singular value decomposition or least squares method can be used to solve equation (2) for values of the vector p.

In some examples, the transformation matrices may then be decomposed into imaging scene parameters. The following equation can be used to relate the matrix P to matrices E and I:

P=I·E  (8)

It should be appreciated that additional terms can be introduced when decomposing the matrix P. For example, the method presented by Tsai, described in “A Versatile Camera Calibration Technique for High-Accuracy 3D Machine Vision Metrology Using of-the-shelf TV Cameras and Lenses”, IEEE Journal of Robotics & Automation, RA-3, No. 4, 323-344, August 1987, which is incorporated herein by reference in its entirety, can be used to correct images 126, 128, for radial distortion.

Matrices E and I contain imaging scene parameters. The following equation represents a composition of the matrix I:

$\begin{matrix} {I = \begin{bmatrix} {sx} & 0 & {- {tx}} \\ 0 & {sy} & {- {ty}} \\ 0 & 0 & {1/f} \end{bmatrix}} & (9) \end{matrix}$

The symbols sx and sy represent values of image coordinate scale factors (e.g., pixel scale factors). The symbol f, representing the focal length, corresponds to the value of the shortest distance between a respective imaging source 130 and the plane of a corresponding image 126, 128. The symbols tx and ty represent the coordinates of the principle point relative to the local origin 125 of the respective image 126, 128. The following equation represents the composition of the matrix E:

$\begin{matrix} {E = \begin{bmatrix} r_{1} & r_{2} & r_{3} & {- \left( {{r_{1} \cdot o_{x}} + {r_{2} \cdot o_{y}} + {r_{3} \cdot o_{z}}} \right)} \\ r_{4} & r_{5} & r_{6} & {- \left( {{r_{4} \cdot o_{x}} + {r_{5} \cdot o_{y}} + {r_{6} \cdot o_{z}}} \right)} \\ r_{7} & r_{8} & r_{9} & {- \left( {{r_{7} \cdot o_{x}} + {r_{8} \cdot o_{y}} + {r_{9} \cdot o_{z}}} \right)} \end{bmatrix}} & (10) \end{matrix}$

The symbols o_(x), o_(y) and oz represent values of the position of the fixator 100 in actual three-dimensional space. The symbols r₁ to r₉ describe the orientation of the fixator 100. These values can be assembled into a three-dimensional rotational matrix R represented by the following equation:

$\begin{matrix} {R = \begin{bmatrix} r_{1} & r_{2} & r_{3} \\ r_{4} & r_{5} & r_{6} \\ r_{7} & r_{8} & r_{9} \end{bmatrix}} & (11) \end{matrix}$

The methods of Trucco and Verri, as described in “Introductory Techniques of 3-D Computer Vision”, Prentice Hall, 1998, or the method of Hartley, as described in “Euclidian Reconstruction from Uncalibrated Views”, Applications of Invariance in Computer Vision, pages 237-256, Springer Verlag, Berlin Heidelberg, 1994, which are incorporated herein in their entireties, can be used to obtain values of the matrices E and/or I. Utilizing the resulting values of matrices E and I, a complete three-dimensional imaging scene of the fixator 100 and the anatomical structure segments 102, 104 can be reconstructed.

For example, FIG. 2 illustrates an example three-dimensional imaging scene reconstructed from the x-ray images 126, 128. In the illustrated embodiment, x-rays are emitted from x-ray imagers 130. It should be appreciated that the x-ray imagers 130 can be the same or different imagers, as described above. The x-rays emitted from the imagers 130 are received on by corresponding imaging devices, thus capturing the images 126, 128. Preferably, the positioning of the imagers 130 with respect to the local origins 125 is known.

In some examples, the images 126, 128 and the imaging scene parameters may then be used to obtain the positions and/or orientations of the anatomical structure segments 102, 104 in three-dimensional space. The position and/or orientation data obtained can be used to develop a treatment plan for a patient, for example to change the orientation and/or position of the fractured first and second anatomical structure segments 102, 104 in order to promote union between the anatomical structure segments 102, 104, as described in more detail below. It should be appreciated that the methods and techniques described herein are not limited to applications of repositioning broken anatomical structures, and that orthopedic fixation with imagery analysis can be used in any other type of fixation procedure as desired, for example lengthening of anatomical structures, correction of anatomical defects, and the like.

In some examples, anatomical structure elements comprising representations of particular portions (e.g., anatomical features) of the anatomical structure segments 102, 104, may then be identified and their locations within the images 126, 128 determined. For example, locations, within the images 126, 128 of the first and the second anatomical structure segments may be indicated using the second image information received at operation 320 and described in detail above. In some examples, the locations of the anatomical structure elements may be determined with respect to the respective local origins 125 of images 126, 128.

The anatomical structure elements can be used in the construction of the three-dimensional representation of the position and/or orientation of the anatomical structure segments 102, 104. Preferably, the anatomical structure elements are easy to identify in the images 126, 128. Points, lines, conics, or the like, or any combination thereof can be used to describe the respective geometries of the anatomical structure elements. For example, in the illustrated embodiment, points 134 and 136 representing the fractured ends 103, 105 of the anatomical structure segments 102, 104, respectively, are identified as anatomical structure elements in the images 126, 128.

The anatomical structure elements can further include marker elements that are implanted into the anatomical structure segments 102, 104 prior to imaging. The marker elements can be used as a supplement to or in lieu of the above-described anatomical structure elements identified in the images 126, 128. The marker elements can be configured for enhanced viewability in the images 126, 128 when compared to the viewability of anatomical features of the anatomical structure segments 102, 104. For example, the marker elements may be constructed of a radio-opaque material, or may be constructed with readily distinguishable geometries.

A three-dimensional representation 200 of the anatomical structure segments 102, 104 can be reconstructed. The three-dimensional representation can be constructed with or without a corresponding representation of the fixator 100. In the illustrated embodiment, pairs of ray-lines, such as ray lines 138, 140 and 142, 144 can be constructed for the anatomical structure element points 134, 136, respectively. Each ray line connects an anatomical structure element in one of the images 126, 128 with a respective imager 130. Each pair of ray lines can be analyzed for a common intersection point, such as points 146, 148. The common intersection points 146, 148 represent the respective positions of the anatomical structure element points 134, 136, in the three-dimensional representation of the anatomical structure segments 102, 104. Of course more than a pair of ray lines, such as a plurality, can be constructed, for example if more than two images were captured. If the ray lines of a particular set do not intersect, a point closest to all the ray lines in the set can be used as the common intersection point.

The positions and/or orientations of the anatomical structure segments 102, 104 can be quantified or measured using common intersection points, for instance points 146, 148. For example, lines representing center lines of the anatomical structure segments 102, 104 can be constructed and can be compared to the anatomical axes of the patient. Additionally, the distance between the fractured ends 103, 105 of the anatomical structure segments 102, 104 can be quantified. Using these or similar techniques, the positions and/or orientations of the anatomical structure segments 102, 104 can be determined. It is further noted that, in some examples, in addition to the positions and orientations of the first and second anatomical structure segments, the positions and orientation of rings (and/or other elements of the fixation apparatus) in three-dimensional space may also be determined, for example using any of the techniques described. For example, in some cases, locations of the rings within the images 126, 128 may be determined based on the first image information and/or other provided information. In some examples, these locations may then be used to determine the positions and orientations of the rings in three-dimensional space. Additionally, in some examples, configuration information for the fixation apparatus, such as ring diameters and strut length and mounting information, may also be used to determine positions and orientations of the rings in three-dimensional space.

Referring now to FIG. 3B, at operation 324, one or more deformity parameters are calculated. The deformity parameters may include parameters relating to the deformity associated with the first and second anatomical structure segments. For example, in some cases, the deformity parameters may include an amount of translation (e.g., lateral, medial, anterior, and/or posterior), a degree of coronal angulation (e.g., valgus and/or varus), a degree of sagittal angulation, an amount by which anatomical structure length is too short and/or too long, a degree of clinical rotational deformity (e.g., internal and/or external), and others. In some examples, the deformity parameters may be calculated as part of the process determining the positions and orientations of the first and segment anatomical structure segments described above at operation 422, for example using the techniques described above with reference to operation 422.

At operation 326, the deformity parameters calculated at operation 424 are displayed, for example using one or more graphical user interfaces of a computing system. Referring now to FIG. 9 , a deformity parameter interface 900 is shown. As shown, interface 900 includes various fields 901-906 for displaying calculated values of various example deformity parameters, including AP View translation and coronal angulation, LAT View translation and sagittal angulation, an amount by which anatomical structure length is too short or too long, and a degree of clinical rotational deformity. In the example of FIG. 9 , fields 901-905 each have a respective PFM badge 915 (including the text “PFM”) that is displayed to the left of each field 901-905. Each PFM badge 915 indicates that the value shown in the respective field 901-905 has been calculated by the software. Interface 900 allows the deformity parameter values that are displayed in each field 901-906 to be edited by a user, for example by typing a number in the fields 901-906 and/or by using number increment controls 916 displayed to the right of each field 901-906. When a user edits a value that was calculated by the software, the PFM badge 915 adjacent to the respective field may be removed to indicate that the value for the field has been edited by the user. In some examples, after editing the values in one or more fields, the user may select Refresh Perspective Frame Matching Data button 920 to return each of the fields to the value that was calculated by the software. Also, in some examples, after editing the values in one or more fields, the user may select Save and Update button 921 to cause the deformity parameters to be recalculated based on the edited values provided by the user, for example by repeating all or any portion of the calculations performed at operation 322.

At operation 328, a graphical representation of the position and orientation of the first and the second anatomical structure segments is generated and displayed. The graphical representation of the position and orientation of the first and the second anatomical structure segments may be displayed using one or more graphical user interfaces of a computing system. For example, as shown in FIG. 9 , interface 900 includes a graphical representation 950 of the position and orientation of the first and the second anatomical structure segments. Graphical representation 950 includes a representation 931 of the proximal anatomical structure segment and a representation 932 of the distal anatomical structure segment. In some examples, the graphical representation 950 may be generated based, at least in part, on the positions and orientations of the first and segment anatomical structure segments determined at operation 322. In some examples, when the user edits one or more deformity parameters and selects Save and Update button 921, the graphical representation 950 may also be adjusted to reflect the saved edits to the deformity parameters. Graphical representation 950 may, for example, improve efficiency and reliability by providing the user with a visual confirmation of information entered into interface 900, for example to allow fast and easy identification of errors or other problems.

At operation 330, one or more mounting parameters are calculated. The mounting parameters may include parameters relating to mounting of a reference ring of the fixator onto a respective anatomical structure segment. For example, in some cases, the mounting parameters may include an amount of offset (e.g., lateral, medial, anterior, and/or posterior) such as for a center of the reference ring with respect to a reference point, a degree of tilt (e.g., proximal and/or distal), an amount of axial offset, a master tab rotation, and others. In some examples, the mounting parameters may be calculated as part of the process determining the positions and orientations of the first and segment anatomical structure segments described above at operation 322, for example using the techniques described above with reference to operation 322. It is noted that, for the process of FIG. 3 , the reference ring is not necessarily required to be orthogonal with respect to the respective anatomical structure segment on which it is mounted. Thus, in some examples, the reference ring may be non-orthogonal with respect to the respective anatomical structure segment on which it is mounted.

At operation 432, the mounting parameters calculated at operation 430 are displayed, for example using one or more graphical user interfaces of a computing system. Referring now to FIG. 10 , a mounting parameter interface 1000 is shown. As shown, interface 1000 includes various fields 1001-1006 for displaying calculated values of various example mounting parameters, including AP View offset and tilt, LAT View offset and tilt, axial offset, and master tab rotation. In the example of FIG. 10 , fields 1001-1006 each have a respective PFM badge 1015 that is displayed to the left of each field 1001-1006. Each PFM badge 1015 indicates that the value shown in the respective field 1001-1006 has been calculated by the software. Interface 1000 allows the mounting parameter values that are displayed in each field 1001-1006 to be edited by a user, for example by typing a number in the fields 1001-1006 and/or by using number increment controls 1016 displayed to the right of each field 1001-1006. When a user edits a value that was calculated by the software, the PFM badge 1015 adjacent to the respective field may be removed to indicate that the value for the field has been edited by the user. In some examples, after editing the values in one or more fields, the user may select Refresh Perspective Frame Matching Data button 1020 to return each of the fields to the value that was calculated by the software. Also, in some examples, after editing the values in one or more fields, the user may select Save and Update button 1021 to cause the deformity parameters to be recalculated based on the edited values provided by the user, for example by repeating all or any portion of the calculations performed at operation 322.

At operation 334, a graphical representation of the position and orientation of the reference ring and the respective anatomical structure segment to which it is mounted is generated and displayed. The graphical representation of the position and orientation of the reference ring and the respective anatomical structure segment may be displayed using one or more graphical user interfaces of a computing system. For example, as shown in FIG. 10 , interface 1000 includes a graphical representation 1050 of the position and orientation of the reference ring and the respective anatomical structure segment. Graphical representation 1050 includes a representation 1031 of the proximal anatomical structure segment, a representation 1033 of the proximal (reference) ring, and a representation 1032 of the distal anatomical structure segment. In some examples, the graphical representation 1050 may be generated based, at least in part, on the positions and orientations of the reference ring and the respective anatomical structure segment determined at operation 322. The graphical representation of the reference ring and the respective anatomical structure segment may, therefore, reflect and/or indicate the positions and orientations of reference ring and the respective anatomical structure segment determined at operation 322. In some examples, when the user edits one or more mounting parameters and selects Save and Update button 1021, the graphical representation 1050 may also be adjusted to reflect the saved edits to the mounting parameters. Graphical representation 1050 may, for example, improve efficiency and reliability by providing the user with a visual confirmation of information entered into interface 1000, for example to allow fast and easy identification of errors or other problems.

At operation 336, one or more treatment plan options are received, for example using one or more graphical user interfaces of a computing system. A treatment plan is a plan for manipulating the fixation apparatus, for example in order to correct the deformity of the first and the second anatomical structure segments. The treatment plan may include, for example, a plan for making gradual adjustments to the positions and orientations of the fixator rings with respect to each other, for example by changing the lengths of the struts of the fixation apparatus. Referring now to FIG. 11 , an example treatment plan interface 1100A is shown. The interface 1100A includes controls for selecting, by a user, various treatment plan options. In particular, controls 1101 and/or 1102 allow selecting of a treatment plan start date, control 1103 allows selection of an option to perform axial movement first (e.g., in an initial part of the treatment, such as prior to rotational movement), control 1104 allows selection of an option to indicate a final distance between reference points, control 1105 allows selection of an option to calculate the treatment plan based on a specified duration (e.g., a number of days) for axial movement, control 1106 allows selection of an option to calculate the treatment plan based on a rate of distraction at the reference point (e.g., for example millimeters (mm)/day) for axial movement, control 1108 allows selection of an option to calculate the treatment plan based on a specified duration (e.g., a number of days) for deformity correction, control 1109 allows selection of an option to calculate the treatment plan based on a rate of distraction at the reference point (e.g., for example millimeters (mm)/day) for deformity correction, and control 1107 allows selection of an option to perform two adjustments per day. In some examples, when control 1007 is not selected, a default option of one adjustment per day may be used. In some examples, after selecting desired treatment plan options, the user may select Update Adjustment Plan button 1110 to trigger generation of the treatment plan. Additionally, after initial generation of the treatment plan, the user may also be permitted to adjust the treatment plan options and have the treatment plan re-generated with the adjusted options by re-selecting Update Adjustment Plan button 1110

At operation 338, manipulations to the fixation apparatus for correction of the anatomical structure deformity (i.e., a treatment plan) are determined. The manipulations to the fixation apparatus may include adjustments to the struts of the fixation apparatus, such as adjustments to the sizes and/or lengths of the struts. In some examples, operation 338 may be performed based, at least in part, on the treatment plan options received at operation 336. For example, operation 338 may be performed based, at least in part, on specified start date, on instructions to perform axial movement first (e.g., in an initial part of the treatment, such as prior to rotational movement), a specified final distance between reference points, instructions to perform additional lengthening by a specified amount, instructions to generate an axial gap to ensure anatomical structure clearance, a specified duration (e.g., a number of days) of treatment, a specified rate of distraction, and/or instructions to perform two perform a specified quantity (e.g., one, two, etc.) of adjustments per day.

In some examples, the treatment plan may also be determined based, at least in part, on a determination of desired changes to the positions and/or orientations of the anatomical structure segments 102, 104, for instance how the anatomical structure segments 102, 104 can be repositioned with respect to each other in order to promote union between the anatomical structure segments 102, 104. For example, in some cases, it may be desirable to change the angulation of the second anatomical structure segment 104 such that the axes L1 and L2 are brought into alignment, and to change the position of the second anatomical structure segment such that the fractured ends 103, 105 of the anatomical structure segments 102, 104 abut each other. Once the desired changes to the positions and/or orientations of the anatomical structure segments 102, 104 have been determined, a treatment plan for effecting the position and/or orientation changes can be determined. In a preferred embodiment, the desired changes to the positions and/or orientations of the anatomical structure segments 102, 104 can be effected gradually, in a series of smaller changes. The positions and/or orientations of the anatomical structure segments 102, 104 can be changed by changing the positions and/or orientations of the upper and lower fixator rings 106, 108 with respect to each other, for instance by lengthening or shortening one or more of the length adjustable struts 116.

The required changes to the geometry of the fixator 100 (i.e., the position and/or orientation of the fixator 100) that can enable the desired changes to the positions and/or orientations of the anatomical structure segments 102, 104 can be computed using the matrix algebra described above. For example, the required repositioning and/or reorientation of the second anatomical structure segment 104 with respect to the first anatomical structure segment 102 can be translated to changes in the position and/or orientation of the lower fixator ring 108 with respect to the upper fixator ring 106.

At operation 340, indications of the determined manipulations to the fixation apparatus are provided to one or more users. For example, in some cases, indications of the determined manipulations to the fixation apparatus may be provided using one or more graphical user interfaces of a computing system, using a printed hard copy, using audio feedback, and/or using other techniques. In particular, referring now to FIG. 12 , it is seen that indications of the determined manipulations to the fixation apparatus may be provided within interface 1100B. Specifically, selection of Strut Adjustment Plan tab 1122 may cause treatment plan interface 1100B to provide a chart 1130, including day-by-day manipulation information for each strut within the fixation apparatus. In this example, chart 1130 shows a length for each strut on each day of treatment. In some examples, one or more alerts may be generated for one or more manipulations to the fixation apparatus that result in at least one of strut movement of more than a threshold amount. For example, in some cases, strut movements exceeding particular threshold amount (e.g., 3 mm per day), which may be referred to as rapid strut movements, may be indicated by displaying a red triangle icon next to the indication of the strut movement in chart 1130. As also shown in FIG. 12 , a PDF version of the chart 1130 may be generated by selecting View Draft PDF button 1131. The generated PDF may, in some examples, be printed to create a hard copy version of chart 1130.

In the example of FIG. 12 , chart 1130 includes blocks 1132-A and 1132-B indicating ranges of dates on which changes of strut sizes, referred to as strut swaps, may be performed. In particular, block 1132-A indicates that a strut swap may be performed for Strut 4 on Day 0 through Day 2, while block 1132-B indicates that a strut swap may be performed for Strut 4 on Day 3 through Day 14 (and subsequent days). In some examples, blocks 1132-A and 1132-B may be color-coded to match a color assigned to a respective strut. For example, blocks 1132-A and 1132-B may be colored green to match a green color that may be assigned to Strut 4. Referring now to FIG. 13 , Strut Swaps Calendar tab 1123 of treatment plan interface 1100-C may be selected to generate a calendar 1140 indicating ranges of dates on which strut swaps may be performed.

In some examples, the struts of the fixation apparatus attached to the patient may be color-coded, for example using color-coded caps, marker, or other color-coded materials included within and/or attached to the struts. In some examples, the physical color-coding of the struts in the fixation apparatus attached to the patient may match the color-coding of struts used in the software. For example, the physical color-coding of the struts in the fixation apparatus may match the color-coding of struts that may be used to color-code the blocks 1132-A and 1132-B of chart 1130, graphical representation 520, and other color-coded representations of the struts displayed by the software. In some examples, this may make it easier for physicians and/or patients to confirm that, when they physically adjust a strut on the fixation apparatus, they are adjusting the correct strut by the correct amount.

At operation 342, one or more graphical representations of the position and orientation of the first and second anatomical structure segments and the rings of the fixation apparatus is generated and displayed. The graphical representation of the position and orientation of the first and the second anatomical structure segments and the rings of the fixation apparatus may be displayed using one or more graphical user interfaces of a computing system. For example, referring back to FIG. 11 , selection of Treatment Simulation tab 1121 may cause interface 1100 to display a graphical representation 1150 of the position and orientation of the first and the second anatomical structure segments and the rings of the fixation apparatus. Graphical representation 1150 includes a representation 1031 of the proximal anatomical structure segment, a representation 1033 of the proximal (reference) ring, a representation 1032 of the distal anatomical structure segment, and a representation 1034 of the distal ring. In some examples, the one or more graphical representations of the position and orientation of the first and second anatomical structure segments and the rings of the fixation apparatus may include day-by-day graphical representations of the position and orientation of the first and second anatomical structure segments and the rings of the fixation apparatus throughout treatment for the anatomical structure deformity. For example, as shown in FIG. 11 , a user may select a particular day of treatment for which to generate and display a graphical representation 1150 using controls 1151, 1152, 1153, and/or 1154. For example, control 1151 may be selected to allow incrementing of the selected day, control 1154 may be selected to allow decrementing of the selected day, and slider 1152 may be slid along bar 1153 to increment and/or decrement the selected day. It is also noted that slider 1152 displays an indication of the currently selected day, which, in the example of FIG. 11 , is treatment day zero. Thus, in FIG. 11 , graphical representation 1150 shows the position and orientation of the first and second anatomical structure segments and the rings of the fixation apparatus at treatment day zero. Using controls 1151-1154 to select a different day of treatment may cause graphical representation 1150 to be adjusted to show the position and orientation of the first and second anatomical structure segments and the rings of the fixation apparatus on the selected different day. As should be appreciated, allowing the surgeon and/or patient to see graphical representations of the position and orientation of the first and second anatomical structure segments and the rings of the fixation apparatus throughout treatment may be beneficial by, for example, providing an additional visual tool to improve accuracy and assist in planning of treatment. Additionally, graphical representation 1150 (as well as graphical representations described herein) may, for example, improve efficiency and reliability by providing the user with a visual confirmation of information entered into interface 1100, for example to allow fast and easy identification of errors or other problems. It is further noted that the view of graphical representation 1150 (as well as other graphical representations described herein) may be rotated (for example by a complete 360 degrees), zoomed in and out, moved in direction, and otherwise manipulated, for example using controls 1181-1184 adjacent to the upper right side of the graphical representation 1150. This may allow views of the first and second anatomical structure segments and/or the rings of the fixation apparatus from various orientations that may not be available, or may be difficult to obtain, using x-rays and other imaging techniques, thereby also improving reliability and accuracy and providing additional visual confirmation of calculated values. In particular, view of the graphical representation 1150 may be rotated using control 1181, zoomed in using control 1182, zoomed out using control 1183, and panned using control 1184. Also, in some examples, other controls, such as a mouse and touchscreen, may also be employed to rotate, zoom, pan, and otherwise manipulate graphical representation 1150. Additionally, in some examples, control 1185 may be used to select an anteroposterior (AP) view, control 1186 may be used to select a lateral view, and control 1187 may be used to select a proximal view.

At operation 344, the treatment plan may be implemented, that is the geometry of the fixation apparatus may be changed, for example based on the manipulations determined at operation 338, in order to change positions and orientations of the anatomical structure segments.

Strut Swap Range Indications

As described above, manipulations to a fixator for correction of an anatomical structure deformity (i.e., a treatment plan) may be determined and implemented. The manipulations to the fixator may include adjustments to the struts of the fixator, such as adjustments to the sizes and/or lengths of the struts. In particular, the manipulations to the fixator may include one or more strut swaps, which is a swap (i.e., exchange) of a replaced strut for a different sized replacement strut by removing the replaced strut from the fixator and replacing it with the replacement strut. A fixator strut is typically capable of being adjusted in size throughout a respective length range, such as from a maximum length to a minimum length. Different sized fixator struts (e.g., large, medium, small) typically have different respective length ranges. Strut swaps may be performed when the treatment plan indicates that the length of the replaced strut is to be reduced to a length that is shorter than a minimum length of the replaced strut—or that the length of the replaced strut is to be increased to a length that a longer than a maximum length of the replaced strut. In some examples, the length ranges of adjacent strut sizes may overlap one another with an overlapping length range (typically 10 millimeters (mm)). For example, in some cases, the minimum length of a medium strut may be 10 mm shorter than the maximum length of a small strut. This overlapping strut range may allow patients to have range of time in which they may perform a strut swap, referred to as a strut swap range. Longer strut swap ranges (e.g., strut swap ranges of several days) may sometimes be beneficial to patients by allowing them greater flexibility in deciding when to perform a particular strut swap.

In some examples, the software may provide three-dimensional day-by-day graphical representations that show the fixator and the anatomical structure segments throughout the course of treatment for the anatomical structure deformity. Described herein are techniques for indicating, within the three-dimensional day-by-day graphical representations, a strut swap range within which a strut swap may be performed. In some examples, these indications may graphically indicate a particular strut on which the strut swap may be performed and may also indicate amounts (e.g., percentages) of time that are remaining and/or elapsed within in the strut swap range.

Referring now to FIG. 14 , an example process for providing a plurality of fixator graphical representations including graphical strut swap range indications will now be described in detail. In particular, the process of FIG. 14 is initiated at operation 1410, at which manipulations to a fixator for correction of a deformity of first and second anatomical structure segments are determined by a computing system. The fixator may include rings and struts. The manipulations may include a plurality of adjustments to strut lengths and a strut swap from a replaced strut to a replacement strut. The manipulations are performed throughout a set of stages, such as any number of days. Thus, in some examples, each stage in the set of stages may be a respective day. A number of example techniques for determining manipulations to a fixator for correcting an anatomical structure deformity are described in detail above (such as with respect to operation 338 of FIG. 3B and based on operations 310-336 of FIGS. 3A-3B) and are not repeated here.

At operation 1412, a strut swap range in which the strut swap is performable is determined by the computing system. The strut swap range comprises a sub-set of stages within the set of stages. For example, the strut swap range may include a particular sub-set of consecutive days within the total set of days over which the treatment plan is implemented. The sub-set of stages may include a swap start stage. The swap start stage is the stage at which the strut swap range starts, such as an initial day of the strut swap range (i.e., the initial day on which the strut swap may be performed). The sub-set of stages may also include a swap end stage. The swap end stage is the stage at which the strut swap range ends, such as a final day of the strut swap range (i.e., the final day on which the strut swap may be performed). The sub-set of stages may also include one or more intermediate stages between the swap start stage and the swap end stage, such as one or more days in between the initial day of the strut swap range and the final day of the strut swap range. The software may determine a strut swap range based on the calculated strut length adjustments in the treatment plan (e.g., as described at operation 334 of FIG. 3B)—and also based on the length ranges of available struts, which may be input to or otherwise made available to the software.

At operation 1414, the plurality of fixator graphical representations are generated by the computing system. The plurality of fixator graphical representations may be displayed in a graphical user interface (GUI) of a computing system. The plurality of fixator graphical representations may be three-dimensional graphical representations of the fixator, such as including three-dimensional graphical representations of the rings and struts of the fixator and three-dimensional graphical representations of the first and the second anatomical structure segments to which the fixator is attached. In some examples, the plurality of fixator graphical representations may include stage-by-stage (e.g., day-by-day) graphical representations of the fixator throughout the course of the treatment plan.

The plurality of fixator graphical representations may include a swap start fixator graphical representation, a swap end fixator graphical representation, and one or more intermediate fixator graphical representations. The swap start fixator graphical representation may represent the fixator at the swap start stage. The swap end fixator graphical representation may represent the fixator at the swap end stage. The one or more intermediate fixator graphical representations may represent the fixator at the one or more intermediate stages between the swap start stage and the swap end stage.

Each of the plurality of fixator graphical representations may include a respective one of a plurality of replaced strut graphical representations and a respective one of a plurality of replacement strut graphical representations. The plurality of replaced strut graphical representations may change from a first rendering state in the swap start fixator graphical representation to a second rendering state in the swap end fixator graphical representation. By contrast, the plurality of replacement strut graphical representations may change from the second rendering state in the swap start fixator graphical representation to the first rendering state in the swap end fixator graphical representation.

In some examples, the first rendering state may be a more opaque state and the second rendering state may be a less opaque state that is less opaque (e.g., more transparent) than the more opaque state. In some examples, the first rendering state may be a mostly opaque state, and the second rendering state may be a mostly transparent state. Additionally, in some examples, the plurality of replaced strut graphical representations and the plurality of replacement strut graphical representations may have linear rates of change between the first rendering state and the second rendering state. In some cases, the one or more intermediate fixator graphical representations may be rendered according to the linear rates of change. Thus, in some examples, the replaced strut graphical representations may gradually fade out from the swap start stage to swap end stage, while the replacement strut graphical representations may gradually fade in from the swap start stage to swap end stage.

Referring now to FIGS. 15-21 , some examples of graphical strut swap range indications will now be described in detail. Specifically, FIG. 15 depicts an interface 1500, such as a graphical user interface (GUI) of a computing system, that includes an example fixator graphical representation 1510 at a first stage (in this example Day 0) of a treatment plan. The graphical representation 1510 includes six strut graphical representations 1511-1516 and ring graphical representations 1517 and 1518. The interface 1500 also includes anatomical structure graphical representations 1551 and 1552. The fixator graphical representation 1510 and the anatomical structure graphical representations 1551 and 1552 are three-dimensional graphical representations that show positions and orientations of the fixator elements (e.g., rings and struts) and the anatomical structure segments in three-dimensional space. The interface 1500 further includes a slide bar 1560 and slider 1561 that can be used to select a desired treatment stage (e.g., day) for which to view a respective fixator graphical representation. In FIG. 15 , the slider 1561 is placed at the start (i.e., left edge) of the slide bar 1560 to select an initial treatment stage (Day 0). In this example, on Day 0 of treatment, none of the struts are currently within a strut swap range.

Referring now to FIG. 16 , an example is shown in which a replaced strut (represented by strut graphical representation 1511) enters into a strut swap range. In particular, as shown in FIG. 16 , a user has moved slider 1561 to the right to switch from a first treatment stage (Day 0) to a second treatment stage (Day 1). Accordingly, a respective fixator graphical representation 1610 corresponding to Day 1 is shown in FIG. 16 . In this example, fixator graphical representation 1610 is a swap start graphical representation that represents the start of a strut swap range for a replaced strut (represented by strut graphical representation 1511). Specifically, the start of the strut swap range is indicated by displaying strut graphical representation 1511 (corresponding to the replaced strut) using a first rendering state, which in this example is a more opaque state. Additionally, FIG. 16 displays a strut graphical representation 1611 corresponding to a replacement strut for which the replaced strut is exchanged during the strut swap range. The start of the strut swap range is further indicated by displaying strut graphical representation 1611 (corresponding to the replacement strut) using a second rendering state, which in this example is a less opaque state. As shown, the less opaque state of replacement strut graphical representation 1611 is less opaque (e.g., more transparent) than the more opaque state of replaced strut graphical representation 1511.

In this example, the strut swap range extends from Day 1 (the swap start stage) to Day 5 (the swap end stage). Thus, Days 2-4 are intermediate stages between the swap start stage and the swap end stage. Accordingly, in this example, the strut swap range indication includes six graphical transitions from 100% opaque to 0% opaque (fully transparent) and vice versa. In this example, the replaced strut graphical representation 1511 and the replacement strut graphical representation 1611 have linear rates of change. Accordingly, for each day of the strut swap range, the replaced strut representation 1511 and the replacement strut graphical representation 1611 are rendered with a 16.66% increase or decrease in opacity from the prior day (corresponding to 100% divided by the six graphical transitions). Thus, in this example, the first rendering state (e.g., more opaque state) that is used for the replaced strut graphical representation 1511 in FIG. 16 (and later used for the replacement strut graphical representation 1611 in FIG. 20 ) corresponds to a state of 83.32% opacity (i.e., 100%-16.66%). Additionally, in this example, the second rendering state (e.g., less opaque state) that is used for the replacement strut graphical representation 1611 in FIG. 16 (and later used for the replaced strut graphical representation 1511 in FIG. 20 ) corresponds to a state of 16.66% opacity (i.e., 0%+16.66%).

Referring now to FIG. 17 , a fixator graphical representation for a third treatment stage (Day 2) is shown. In particular, as shown in FIG. 17 , a user has moved slider 1561 further to the right to switch from Day 1 to Day 2. Accordingly, a respective fixator graphical representation 1710 corresponding to Day 2 is shown in FIG. 17 . In this example, Day 2 is the second of five days from the start to the end of the strut swap range. In this example, the replaced strut graphical representation 1511 and the replacement strut graphical representation 1611 have linear rates of change between the first rendering state and the second rendering state. This is indicated by displaying replaced strut graphical representation 1511 in fixator graphical representation 1710 using an intermediate rendering state that represents a state of 66.66% opacity, which is a decrease of 16.66% from the rendering state of 83.32% opacity of replaced strut graphical representation 1511 in FIG. 16 . Additionally, replacement strut graphical representation 1611 is displayed in fixator graphical representation 1710 using an intermediate rendering state that represents a state of 33.33% opacity, which is an increase of 16.66% from the rendering state of 16.66% opacity of replacement strut graphical representation 1611 in FIG. 16 . Thus, in FIG. 17 , the replaced strut graphical representation 1511 is still more opaque than the replacement strut graphical representation 1611, but the contrast (i.e., difference in opacity) is not as much as in FIG. 16 .

Day 3 is a midpoint stage halfway between the swap start stage and the swap end stage. Referring now to FIG. 18 , a fixator graphical representation for a fourth treatment stage (Day 3) is shown. In particular, as shown in FIG. 18 , a user has moved slider 1561 further to the right to switch from to switch from Day 2 to Day 3. Accordingly, a respective fixator graphical representation 1810 corresponding to Day 3 is shown in FIG. 18 . In this example, Day 3 is the third of five days from the start to the end of the strut swap range. Thus, Day 3 is fifty percent of the elapsed time period (i.e., halfway) from the swap start stage to the swap end stage. This is indicated by displaying both replaced strut graphical representation 1511 and replacement strut graphical representation 1611 in fixator graphical representation 1810 using an intermediate rendering state of 50% opacity. Thus, in FIG. 18 , the replaced strut graphical representation 1511 and the replacement strut graphical representation 1611 have the same level of opacity to indicate that Day 3 is the midpoint of the strut swap range.

Referring now to FIG. 19 , a fixator graphical representation for a fifth treatment stage (Day 4) is shown. In particular, as shown in FIG. 19 , a user has moved slider 1561 further to the right to switch from Day 3 to Day 4. Accordingly, a respective fixator graphical representation 1910 corresponding to Day 4 is shown in FIG. 19 . In this example, Day 4 is the fourth of five days from the start to the end of the strut swap range. This is indicated by displaying replaced strut graphical representation 1511 in fixator graphical representation 1910 using an intermediate rendering state of 33.33% opacity, which is a decrease of 16.66% from the rendering state of 50% opacity of replaced strut graphical representation 1511 in FIG. 18 . Additionally, replacement strut graphical representation 1611 is displayed in fixator graphical representation 1710 using an intermediate rendering state of 66.66% opacity, which is an increase of 16.66% from the rendering state of 50% opacity of replacement strut graphical representation 1611 in FIG. 18 . Thus, in FIG. 19 , the replaced strut graphical representation 1511 is now less opaque than the replacement strut graphical representation 1611, thereby indicating that the strut swap range is more than halfway elapsed.

Referring now to FIG. 20 , a fixator graphical representation for a sixth treatment stage (Day 5) is shown. In particular, as shown in FIG. 20 , a user has moved slider 1561 further to the right to switch from Day 4 to Day 5. Accordingly, a respective fixator graphical representation 2010 corresponding to Day 5 is shown in FIG. 20 . In this example, fixator graphical representation 2010 is a swap end fixator graphical representation that represents the end of the strut swap range. Specifically, the end of the strut swap range is indicated by displaying replaced strut graphical representation 1511 using the second rendering state, which in this example is a less opaque state (e.g., 16.66% opacity). Thus, replaced strut graphical representation 1511 is shown in FIG. 20 (for the swap end stage) with the same level opacity (16.66% opacity) used for the replacement strut graphical representation 1611 in FIG. 16 (for the swap start stage). Additionally, FIG. 20 displays replacement strut graphical representation 1611 using the first rendering state, which in this example is the more opaque state (e.g., 83.32% opacity). Thus, replacement strut graphical representation 1611 is shown in FIG. 20 (for the swap end stage) with the same level opacity (83.32% opacity) used for the replaced strut graphical representation 1511 in FIG. 16 (for the swap start stage). Accordingly, it can be seen that, at the start of strut swap range (FIG. 16 ), the replaced strut graphical representation is shown as mostly opaque and then gradually fades out over the course of the strut swap range until it is mostly transparent at the end of the strut swap range (FIG. 20 ). By contrast, at the start of strut swap range (FIG. 16 ), the replacement strut graphical representation is shown as mostly transparent and then gradually fades in over the course of the strut swap range until it is mostly opaque at the end of the strut swap range (FIG. 20 ). In this manner, fixator graphical representations 1610-2010 may provide visual indications of a particular strut that is in a swap range—and visual indications of an amount (e.g., percentage) of time that has elapsed and/or that remains in the strut swap range.

Referring now to FIG. 21 , a fixator graphical representation for a seventh treatment stage (Day 6) is shown. In particular, as shown in FIG. 21 , a user has moved slider 1561 further to the right to switch from Day 5 to Day 6. Accordingly, a respective fixator graphical representation 2110 corresponding to Day 6 is shown in FIG. 21 . In this example, fixator graphical representation 2110 represents the fixator after conclusion of the strut swap range. As shown, the replaced strut graphical representation 1511 is no longer shown and has instead been replaced by replacement strut graphical representation 1611 within the fixator graphical representation 2110.

Interfamily Strut Swaps

In some examples, there may be various different strut families that may be available for use with a fixator. A family of struts, as that term is used herein, is a group of struts of different sizes (e.g., small, medium, large, etc.) whose length may be adjusted using a common length adjustment technique. Different strut families may therefore have different length adjustment techniques with respect to one another. Two example strut families are a standard strut family and a quick adjust strut family. In some examples, standard struts may have their lengths adjusted by turning a locking collar until it is out of the way, and then turning a length adjustment knob until a length indicator is in line with a planned length. At that point, the locking collar may be returned to be in firm direct contact with the adjustment knob without allowing either of them to twist. By contrast, in some examples, quick adjust struts may have their lengths adjusted by pushing in on an adjustment knob and turning until a click is heard. The adjustment knob may be turned as many times as needed to get the length indicator in line with the planned length. In some examples, the quick adjust struts may be adjusted in a quick and efficient fashion and may reduce inadvertent strut movements.

One limitation of at least some conventional software applications in this field is that the software may be limited to generating treatment plans that include only intrafamily strut swaps (i.e., swaps within a single strut family) as opposed to interfamily strut swaps (i.e., swaps between different strut families). One disadvantage of this limitation is that the strut lengths of different families may differ from one another. In some examples, the maximum length of a longest strut in one family may be longer than the maximum length of a longest strut in a different family. Additionally, the minimum length of a shortest strut in one family may be shorter than the minimum length of a shortest strut in a different family.

For example, consider a scenario in which a maximum length of a longest quick adjust strut is longer than a maximum length of a longest standard strut. Now suppose that there is a clinical case in which standard struts are selected for use. Also suppose that, for completion, the clinical case requires a particular strut length that is longer than the maximum length of the longest standard strut but that could be completed using the longest quick adjust strut. In this example, conventional software techniques that allow only intrafamily strut swaps may not allow a swap from a standard strut to the longest quick adjust strut in order to achieve the longer strut length.

As another example, consider a scenario in which a minimum length of a shortest standard strut is shorter than a minimum length of a shortest quick adjust strut. Now suppose that there is a clinical case in which quick adjust struts are selected for use. Also suppose that, for completion, the clinical case requires a particular strut length that is shorter than the minimum length of the shortest quick adjust strut but that could be completed using the shortest standard strut. In this example, conventional software techniques that allow only intrafamily strut swaps may not allow a swap from a quick adjust strut to the shortest standard strut in order to achieve the shorter strut length.

In order to alleviate the above and other problems, techniques are described herein in which a treatment plan may be generated that may include interfamily strut swaps between struts of different families. Referring now to FIG. 22 , an example process for generating a treatment plan including an interfamily strut swap will now be described in detail. The treatment plan is for manipulating a fixator including rings and struts to correct a deformity of first and second anatomical structure segments. The process of FIG. 22 is initiated at operation 2210, at which positions and orientations of the first and second anatomical structure segments in three-dimensional space are determined by a computing system. Various example processes for determining positions and orientations of the first and second anatomical structure segments in three-dimensional space are described in detail above (such as with respect to operation 322 of FIG. 3A and based on operations 310-322 of FIG. 3A), for example using the frame matching processes described above. In some examples, images of the anatomical structure segments and the fixator attached thereto may be acquired, indications of known geometries (e.g., geometries of fixator elements) and of locations of fixator elements and anatomical structure segments in the images may be received and used to determine the positions and orientations of the first and second anatomical structure segments in three-dimensional space.

At operation 2212, manipulations to the fixator for correction of the deformity are determined by the computing system. A number of example techniques for determining manipulations to a fixator for correcting an anatomical structure deformity are described in detail above (such as with respect to operation 338 of FIG. 3B and based on operations 310-338 of FIGS. 3A-3B) and are not repeated here. In some examples, the manipulations may be determined by determining desired changes to the positions and/or orientations of the anatomical structure segments, for instance how the anatomical structure segments can be repositioned with respect to each other in order to promote union between the anatomical structure segments. The required changes to the geometry of the fixator hat can enable the desired changes to the positions and/or orientations of the anatomical structure segments can be computed, for example using the matrix algebra described above. In some examples, the manipulations may be determined based at least in part on various treatment plan options (e.g. duration, distraction rate, etc.) such as described above with reference to operation 336 of FIG. 3B.

As set forth above, the manipulations include a plurality of adjustments to strut lengths. In the example of FIG. 22 , however, the determined manipulations may also include an interfamily strut swap between a first strut in a first strut family and a second strut in a second strut family. As set forth above, a strut swap is a swap (i.e., exchange) of a replaced strut for a different sized replacement strut by removing the replaced strut from the fixator and replacing it with the replacement strut. As set forth above, certain conventional software programs may allow only intrafamily strut swaps between struts within the same family. By contrast, the manipulations determined at operation 2212 include at least one interfamily strut swap from a first strut in a first strut family to a second strut in a second strut family. The first strut family may include a first plurality of struts having different size ranges with respect to one another and the second strut family may include a second plurality of struts having different size ranges with respect to one another. In some examples, the first strut family may be a standard strut family and the second strut family may be a quick adjust strut family. In other examples, the first strut family may be a quick adjust strut family and the second strut family may be a standard strut family. In some examples, a first maximum length of a longest strut in the first strut family may be longer than a second maximum length of a longest strut in the second strut family. For example, in some cases, a maximum length of a longest quick adjust strut may be longer than a maximum length of a longest standard strut. Also, in some examples, a first minimum length of a shortest strut in the first strut family may be shorter than a second minimum length of a shortest strut in the second strut family. For example, a minimum length of a shortest standard strut may be shorter than a minimum length of a shortest quick adjust strut. Thus, by allowing at least one interfamily strut swap, the treatment plan may allow struts to be lengthened and/or shortened to lengths that may not be achievable using on only intrafamily strut swaps between struts in a single family.

As should be appreciated, the ability to include interfamily strut swaps in a treatment plan may raise the complexity of calculating the treatment plan because, in some cases, multiple different possible combinations of different strut swaps could be employed in order to eventually result in correction of the deformity, for example because size ranges of struts from different families may at least partially overlap one another at various different lengths. In some examples, a number of optimization rules may be employed in order to allow the software to select and calculate a particular treatment plan (i.e., set of strut adjustments) from a number of potential available treatment plans. For example, an inclusion of the interfamily strut swap in the manipulations may be based on a determination that the correction of the deformity cannot be performed using struts from only a single strut family. In some cases, a user may select a preferred strut family. If the correction can be accomplished using only struts from the preferred strut family, then a treatment plan may be generated that includes only intrafamily strut swaps within the preferred strut family. Interfamily strut swaps may be employed only when it is determined that the correction cannot be accomplished using only struts from the preferred strut family.

In some examples, if the correction can be accomplished only by using at least one strut from a non-preferred family, then a decision tree may be created that represents all possible strut swap scenarios for a given strut based on the initially mounted strut type and the strut length values for each treatment step. Different paths through the decision tree may then represent different strut swap plans. For each strut node in the tree, a cost function may calculate the costs of a potential strut swap between a parent strut type and a current strut type. These cost functions may allow the optimization and selection of a strut swap plan. In some examples, the strut swap plan may be created according to the path through the decision tree with the lowest costs. In some examples, a potential goal of the optimization may include reducing the number of required strut swaps in the selected strut swap plan. In some cases, this goal may be accomplished by assigning a higher cost to the act of performing each additional strut swap in comparison to other cost factors (e.g., strut swap range duration, etc.). In some examples, the manipulations to the fixator may be determined based at least in part on a rule to select a treatment plan with a fewest amount of strut swaps from a plurality of available treatment plans. Another potential goal of the optimization may include optimizing the strut swap range duration in the selected strut swap plan. Specifically, in some cases, longer strut swap range durations (e.g., durations of four or more days) may be preferred because they may give patients greater flexibility in selecting when strut swaps are performed. In some cases, this goal may be accomplished by assigning a higher cost to shorter strut swap range durations in comparison to other cost factors (e.g., quantity of strut swaps, etc.). In some examples, the manipulations to the fixator may be determined based at least in part on a rule to select a treatment plan with at least one strut swap having at least a minimum threshold strut swap duration (e.g., at least four days) from a plurality of available treatment plans.

At operation 2214, indications of the manipulations to the fixator are provided, by the computing system, to one or more users. Various example techniques for providing indications of manipulations to a fixator are described above, for example with respect to operations 340-342 of FIG. 3B and FIGS. 11-13 . For example, chart 1130 of FIG. 12 may include day-by-day manipulation information for each strut within the fixation apparatus. Additionally, a calendar 1140 of FIG. 13 may indicate ranges of dates on which strut swaps may be performed. Furthermore, day-by-day graphical representations of the fixator that indicate strut swap ranges, for example as shown in FIGS. 15-21 and described above, may also be employed. It is noted that, in some examples, the strut swap range indication techniques described above, such as with respect to FIG. 14 , may be used to indicate swap ranges for either or both of intrafamily and interfamily strut swaps. Any combination of these and other techniques may be used. Upon being provided with the indications of the manipulations to the fixator, one or more users may implement the indicated adjustments, including performing one or more interfamily strut swaps, in order to correct the deformity of the anatomical structure segments.

Example Computing Device

Referring to FIG. 23 , a suitable computing device such as example computing device 78 can be configured to perform any or all of the techniques set forth above. It will be understood that the computing device 78 can include any appropriate device, examples of which include a desktop computing device, a server computing device, or a portable computing device, such as a laptop, tablet, or smart phone.

In an example configuration, the computing device 78 includes a processing portion 80, a memory portion 82, an input/output portion 84, and a user interface (UI) portion 86. It is emphasized that the block diagram depiction of the computing device 78 is exemplary and not intended to imply a specific implementation and/or configuration. The processing portion 80, memory portion 82, input/output portion 84, and user interface portion 86 can be coupled together to allow communications therebetween. As should be appreciated, any of the above components may be distributed across one or more separate devices and/or locations.

In various embodiments, the input/output portion 84 includes a receiver of the computing device 78, a transmitter of the computing device 78, or a combination thereof. The input/output portion 84 is capable of receiving and/or providing information pertaining to communicate a network such as, for example, the Internet. As should be appreciated, transmit and receive functionality may also be provided by one or more devices external to the computing device 78.

The processing portion 80 may include one or more processors. Depending upon the exact configuration and type of processor, the memory portion 82 can be volatile (such as some types of RAM), non-volatile (such as ROM, flash memory, etc.), or a combination thereof. The computing device 78 can include additional storage (e.g., removable storage and/or non-removable storage) including, but not limited to, tape, flash memory, smart cards, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, universal serial bus (USB) compatible memory, or any other medium which can be used to store information and which can be accessed by the computing device 78.

The computing device 78 also can contain the user interface portion 86 allowing a user to communicate with the computing device 78. The user interface 86 can include inputs that provide the ability to control the computing device 78, via, for example, buttons, soft keys, a mouse, voice actuated controls, a touch screen, movement of the computing device 78, visual cues (e.g., moving a hand in front of a camera on the computing device 78), or the like. The user interface portion 86 can provide outputs, including visual information (e.g., via a display), audio information (e.g., via speaker), mechanically (e.g., via a vibrating mechanism), or a combination thereof. In various configurations, the user interface portion 86 can include a display, one or more graphical user interfaces, a touch screen, a keyboard, a mouse, an accelerometer, a motion detector, a speaker, a microphone, a camera, a tilt sensor, or any combination thereof. Thus, a computing system including, for example, one or more computing devices 78 can include a processor, a display coupled to the processor, and a memory in communication with the processor, one or more graphical user interfaces, and various other components. The memory can have stored therein instructions that, upon execution by the processor, cause the computer system to perform operations, such as the operations described above. As used herein, the term computing system can refer to a system that includes one or more computing devices 78. For instance, the computing system can include one or more server computing devices that communicate with one or more client computing devices.

While example embodiments of devices for executing the disclosed techniques are described herein, the underlying concepts can be applied to any computing device, processor, or system capable of communicating and presenting information as described herein. The various techniques described herein can be implemented in connection with hardware or software or, where appropriate, with a combination of both. Thus, the methods and apparatuses described herein can be implemented, or certain aspects or portions thereof, can take the form of program code (i.e., instructions) embodied in tangible non-transitory storage media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium (computer-readable storage medium), wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for performing the techniques described herein. In the case of program code execution on programmable computers, the computing device will generally include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device, for instance a display. The display can be configured to display visual information. The program(s) can be implemented in assembly or machine language, if desired. The language can be a compiled or interpreted language, and combined with hardware implementations.

It should be appreciated that the orthopedic fixation with imagery analysis techniques described herein provide not only for the use of non-orthogonal images, but also allow the use of overlapping images, images captured using different imaging techniques, images captured in different settings, and the like, thereby presenting a surgeon with greater flexibility when compared with existing fixation and imagery techniques.

The techniques described herein also can be practiced via communications embodied in the form of program code that is transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via any other form of transmission. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates to invoke the functionality described herein. Additionally, any storage techniques used in connection with the techniques described herein can invariably be a combination of hardware and software.

While the techniques described herein can be implemented and have been described in connection with the various embodiments of the various figures, it is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments without deviating therefrom. For example, it should be appreciated that the steps disclosed above can be performed in the order set forth above, or in any other order as desired. Further, one skilled in the art will recognize that the techniques described in the present application may apply to any environment, whether wired or wireless, and may be applied to any number of such devices connected via a communications network and interacting across the network. Therefore, the techniques described herein should not be limited to any single embodiment, but rather should be construed in breadth and scope in accordance with the appended claims. 

What is claimed:
 1. A computer-implemented method for providing a plurality of fixator graphical representations of a fixator that includes rings and struts to correct a deformity of first and second anatomical structure segments comprising: determining, by a computing system, manipulations to the fixator for correction of the deformity, the manipulations to the fixator comprising a plurality of adjustments to strut lengths and a strut swap from a replaced strut to a replacement strut, wherein the manipulations to the fixator are performed throughout a set of stages, wherein the strut swap is performable in a strut swap range comprising a sub-set of stages within the set of stages, the sub-set of stages including a swap start stage and a swap end stage; and generating, by the computing system, the plurality of fixator graphical representations, wherein the plurality of fixator graphical representations include a swap start fixator graphical representation and a swap end fixator graphical representation, wherein each of the plurality of fixator graphical representations includes a respective one of a plurality of replaced strut graphical representations, and wherein the plurality of replaced strut graphical representations change from a first rendering state in the swap start fixator graphical representation to a second rendering state in the swap end fixator graphical representation.
 2. The computer-implemented method of claim 1, wherein each stage in the set of stages is a respective day.
 3. The computer-implemented method of claim 1, wherein the first rendering state is a more opaque state and the second rendering state is a less opaque state that is less opaque than the more opaque state.
 4. The computer-implemented method of claim 1, wherein the plurality of replaced strut graphical representations have a linear rate of change between the first rendering state and the second rendering state.
 5. The computer-implemented method of claim 4, wherein the plurality of fixator graphical representations include one or more intermediate fixator graphical representations that represent the fixator at one or more intermediate stages between the swap start stage and the swap end stage, and wherein the one or more intermediate fixator graphical representations are rendered according to the linear rate of change.
 6. The computer-implemented method of claim 1, wherein the plurality of fixator graphical representations are three-dimensional graphical representations of the fixator.
 7. The computer-implemented method of claim 1, wherein each of the plurality of fixator graphical representations further includes a respective one of a plurality of replacement strut graphical representations.
 8. A computer-implemented method comprising: determining, by a computing system, positions and orientations of first and second anatomical structure segments in three-dimensional space, wherein a fixator including rings and struts is manipulated for correction of a deformity of the first and the second anatomical structure segments; determining, by the computing system, manipulations to the fixator for the correction of the deformity, the manipulations to the fixator comprising a plurality of adjustments to strut lengths, wherein the manipulations to the fixator are determined based at least in part on a rule to select a treatment plan with at least one strut swap having at least a minimum strut swap duration from a plurality of available treatment plans; and providing, by the computing system, to one or more users, indications of the manipulations to the fixator.
 9. The computer-implemented method of claim 8, further comprising determining that the correction of the deformity cannot be performed using struts from only a single strut family.
 10. The computer-implemented method of claim 8, further comprising creating a decision tree that represents strut swap scenarios for a given strut based on an initially mounted strut type and strut length values for treatment steps.
 11. The computer-implemented method of claim 10, wherein different paths through the decision tree represent different strut swap plans.
 12. The computer-implemented method of claim 10, wherein, for each strut node in the decision tree, a cost function calculates a cost of a potential strut swap.
 13. The computer-implemented method of claim 10, further comprising creating a strut swap plan according to a lowest cost path through the decision tree.
 14. A computing system comprising: one or more processors; and one or more memories having stored therein instructions that, upon execution by the one or more processors, cause the computing system to perform operations for providing a plurality of fixator graphical representations of a fixator that includes rings and struts to correct a deformity of first and second anatomical structure segments, the operations comprising: determining, by the computing system, manipulations to the fixator for correction of the deformity, the manipulations to the fixator comprising a plurality of adjustments to strut lengths and a strut swap from a replaced strut to a replacement strut, wherein the manipulations to the fixator are performed throughout a set of stages, wherein the strut swap is performable in a strut swap range comprising a sub-set of stages within the set of stages, the sub-set of stages including a swap start stage and a swap end stage; and generating, by the computing system, the plurality of fixator graphical representations, wherein the plurality of fixator graphical representations include a swap start fixator graphical representation and a swap end fixator graphical representation, wherein each of the plurality of fixator graphical representations includes a respective one of a plurality of replaced strut graphical representations, and wherein the plurality of replaced strut graphical representations change from a first rendering state in the swap start fixator graphical representation to a second rendering state in the swap end fixator graphical representation.
 15. The computing system of claim 14, wherein each stage in the set of stages is a respective day.
 16. The computing system of claim 14, wherein the first rendering state is a more opaque state and the second rendering state is a less opaque state that is less opaque than the more opaque state.
 17. The computing system of claim 14, wherein the plurality of replaced strut graphical representations have a linear rate of change between the first rendering state and the second rendering state.
 18. The computing system of claim 17, wherein the plurality of fixator graphical representations include one or more intermediate fixator graphical representations that represent the fixator at one or more intermediate stages between the swap start stage and the swap end stage, and wherein the one or more intermediate fixator graphical representations are rendered according to the linear rate of change.
 19. The computing system of claim 14, wherein the plurality of fixator graphical representations are three-dimensional graphical representations of the fixator.
 20. The computing system of claim 14, wherein each of the plurality of fixator graphical representations further includes a respective one of a plurality of replacement strut graphical representations. 